Research on the Deformation and Control Technology of Surrounding Rock in Entry Retaining along the Gob Side

Table 1

Mechanical parameters of coal.

Name	Type	Compressive strength (MPa)	Tensile strength (MPa)	Cohesion (MPa)	Internal friction angle (MPa)	Modulus of elasticity (GPa)	Poisson’s ratio
Main roof	Packsand	46.63	4.96	7.76	36	28.85	0.20
Direct roof	Sandy mudstone	23.44	3.85	4.68	33	3.69	0.27
3# coal	3# coal	9.49	1.12	2.12	30	1.53	0.27
Direct floor	Siltstone	28.51	3.71	5.98	35	24.49	0.17